1. Field of the Invention
The invention relates generally to materials and methods for forming barrier layers and, more particularly, to a material and method for forming a barrier layer over a contaminated, underwater surface.
2. Summary of Related Art
A significant number of lakes, ponds, marshes, river beds and the like are contaminated with environmentally hazardous materials. Examples of such materials include polychlorinated biphenyls, or PCBs, white phosphorus, and metals. Many of these materials, once introduced by one means or another, settle on the bottoms of such bodies of water. This contaminated sediment is detrimental to the wildlife which utilizes the body of water, especially to the fish and foraging waterfowl.
In some cases, it is not feasible to remove or treat such sediment in situ. Thus, to prevent the wildlife from coming into contact with the contaminated sediment, it has been proposed to form a barrier layer over the contaminated sediment. To accomplish that, various plastic membrane barrier systems have been used previously. Such systems typically include a plastic membrane which is positioned on the bottom of the body of water with a layer of sand or similar material over the top of the plastic membrane to hold it in position. A number of venting pipes are usually required to permit the venting of gases which build up beneath the plastic membrane. These plastic membrane systems are relatively difficult and expensive to install. In addition, the plastic membranes are relatively easily punctured and are susceptible to cracking in response to the large temperature changes experienced in many underwater environments.
It would therefore be desirable to provide a relatively simple and inexpensive material for forming a barrier layer over a contaminated, underwater surface which is durable under varied temperature conditions. It would further be desirable to provide such a material which forms a barrier layer which is not susceptible to puncture or cracking and which does not require a venting system. It would also be desirable to provide an improved method of forming such a barrier layer.